It began when a Denver patrol officer stopped a young man who had just left Shotgun Willie's strip club driving a Jeep with illegal flashing red lights and a blaring siren last month. Then the officer spotted a machine gun among an arsenal of weapons in the Jeep.

Now, 21-year-old Andrew Thomas Gunzner, an apprentice gunsmith at a Littleton gun shop, has been indicted by a federal grand jury on charges of possessing two machine guns that he stole from his employer, Prairie Arms Manufacturing, and possessing explosive devices, the Colorado U.S. Attorney's Office told TheDenverChannel.com Tuesday.

The charges carry a maximum penalty of 40 years in prison and $760,000 in fines. Gunzner remains in Denver jail.

The indictment of the Littleton area man culminated a month-long investigation by Denver police and federal Bureau of Alcohol, Tobacco, Firearms and Explosives agents.

Neighbors in the suspect's upscale Littleton area neighborhood were stunned two weeks ago when police and federal agents raided Gunzner's home and found it filled with 14 other shotguns, rifles and pistols, three "destructive devices," chemical explosives, and a notebook with a handwritten bomb diagram, according to the search warrant inventory of items seized.

Police also seized a bullet-proof vest, 12 high-capacity bullet-clips and several cans and boxes of ammunition, including .50-caliber bullets.

"Surprising to say the least," said Matthew Aiken, a neighbor of Gunzner. "Wow. This is a quiet neighborhood where you would want to live. [It] doesn't seem like that can happen here."

He has told his boss that he "worked security" for country-singing star Carrie Underwood and she gave him a pistol as a gift, the affidavit said.

Gunzner's attorney did not want to comment on the case at this time.

Gunzner's life began to unravel when the patrol officer spotted him driving with lights and sirens south on Colorado Boulevard near Cherry Creek Drive at 2:25 a.m. on March 17.

The silver Jeep contained a small arsenal, police said. Besides the four guns, police found several handgun ammunition clips, ammunition, handcuffs, an expandable police baton, knives, holsters and a military-style rifle scope, the affidavit said.

Police arrested Gunzner and took him in for questioning.

When the officer asked Gunzner what authority he had to use the flashing lights and sirens, the man said he was a volunteer firefighter with the Foothills Fire Department and must have accidentally switched the equipment on, the affidavit said.

But an operations captain for the fire agency later told investigators he had no record of Gunzner volunteering at the department.

"Gunzner was in no way any type of emergency responder and was only doing (the flashing lights and siren) for fun," Denver police Detective James Anderson wrote in the affidavit.

Gunzner acknowledged that, after working the night at the Prairie Arms, he'd gone to the strip club on Colorado Boulevard, the affidavit said. He said he'd had two shots of an unspecified liquor and left at closing time.

Jackson told investigators he'd left the store with Gunzner earlier that night and later met him for dinner at the Red Robin restaurant.

"Jackson stated that Gunzner had been talking about a girl he met at the strip club, whom he was attempting to date," the affidavit said. The two men left the restaurant about 9:30 p.m.

When a federal Bureau of Alcohol, Tobacco, Firearms and Explosives investigator visited Prairie Arms Manufacturing the morning after Gunzner's arrest, owner Jackson and a manager did a quick inventory and found that a Heckler & Koch machine gun was missing from the store's large gun safe, the affidavit said. Other guns and equipment were found missing later.

Jackson said, besides himself and the manager, only Gunzner had the safe combination, because part of his job was putting guns out on display, the affidavit said. Jackson added that Gunzner hadn't been in the gun safe for several weeks.

"Jackson reiterated that Gunzner absolutely did not have permission to take any firearms from the store," the affidavit said.

Gunzner told police that he did have permission to remove guns from the store when he was test-firing them or giving demonstrations, but hadn't been doing such activities at the time he was arrested, the affidavit said.

Gunzner admitted the store owner hadn't given him permission to remove the machine gun, but he "took the MP-5 out of the store to 'play' with it," the affidavit said.